In recent years, there has been a need to develop magnetic components having high performance suitable for use as important functional components as electronic equipment having a small size, light weight and high performance. In particular, in switching power sources used as power sources of OA equipment and communication equipment, high frequency is required due to the requirement of small size and light weight. Accordingly, magnetic materials used in these magnetic components must have excellent high frequency magnetic characteristics. In particular, materials having high permeability are effective for many magnetic components such as residual current transformers, current sensors and noise filters.
In recent years, switching power sources having magnetic amplifiers incorporated therein have been widely used from the standpoints of high reliability and high efficiency.
The main part constituting the magnetic amplifier is a saturable reactor, and magnetic materials having excellent squareness and magnetization characteristics are required. Heretofore, Sendelta (tradename) composed of an Fe-Ni crystalline alloy has been used as such a magnetic material.
While Sendelta has excellent squareness magnetization characteristics, its coercive force is increased at a high frequency of 20 kHz or higher and its eddy-current loss is increased to generate heat, whereby Sendelta becomes unusable. Therefore, the switching frequency of the switching power source having a magnetic amplifier incorporated therein is restricted to no more than 20 kHz.
In recent years, there has been a demand for switching power sources having higher switching frequency in addition to small size and light weight. Japanese Patent Laid-Open Publication No. 225804/1986 discloses an amorphous alloy suitable for use as a magnetic material having a small coercive force at a high frequency and excellent squareness characteristic and heat stability.
In order to meet requirements of high efficiency of the switching power source, it is necessary to provide an amorphous alloy magnetic core having high performance, and particularly it is desirable that the squareness ratio and magnetic saturation characteristic (e.g., the reduction in saturation inductance) of magnetic amplifiers used at a frequency of at least 50 kHz be further improved.